CONTACT LENS
A hydrophilizingly coated silicone contact lens has a radial cross-section of the inner face (1), the rim portion contour of which is convex (7) between a point of inflection (6) and the outer edge. For its manufacture, a silicone precursor is brought between a female and a male mold and is polymerized, and the polymerized contact lens is released from the mold by means of a liquid swelling same and is completed after a PECVD/CVD-coating without edge cutting.
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The present application relates to a “soft” contact lens with excellent wearing properties.
Conventional contact lenses, e. g. those known from the German utility model publication G 87 10 765 U1, have a radially inner part made of a harder material, and a radially outer part made of a softer material. The inner surface is entirely concave and the outer surface entirely convex, i.e. both surfaces have a positive Gaussian curvature. This known lens is not satisfactory with regard to its wearing comfort.
It is also known to apply a hydrophilic coating to a contact lens made of poly(methyl methacrylate), PMMA (U.S. Pat. No. 5,080,924). Still, the wearing comfort of such lenses is not perceived as satisfactory.
The invention aims at providing a contact lens having good or even excellent wearing comfort, and a method for its manufacture.
This problem is solved by a contact lens made of silicone, wherein a radial cross section on the inner face has a rim region between a point of inflection and the outer edge in which the cross section contour is convex, in particular with a radius of between 0,1 and 10 mm. Because of this rim contour, the lens particularly readily slips onto the tear liquid film.
In embodiments, the contact lens has a surface layer made of a hydrophilic material auf, which further improves on the wearing comfort.
According to another aspect, the problem is solved by a process in which a silicone precursor material is brought in between a female and a male mold and is polymerised, and the polymerised contact lens is removed from the mold by means of a liquid swelling the contact lens and completed without edge cutting. Thereby the occurrance of a cutting edge, which might be perceived as irritating, is avoided.
In embodiments, the raw lens thus obtained is hydrophilized in a combined PECVD/CVD-process, whereby particularly thick coatings are achieved.
Further features of the invention are available from the subsequent description of embodiments in conjunction with the claims and the drawings. The invention is not limited to the described embodiments, but defined by the scope of the appended claims. In particular, individual features of embodiments of the invention may be realized in a different number or combination than in the examples explained hereunder. In the following explanation of embodiments reference is made to the appended drawings, which show:
The general shape of a contact lens is shown in Figures la and lb: The inner face 1 facing the cornea, which face, in use, floats on a film of tear liquid, is concave in its central part Z, namely rotationally symmetric-aspheric with a conus coefficient of about −0.1 to −0.5, thus somewhat elliptically pointed. In principle, this face also may deviate from the rotational symmetry if required by the physiological conditions. The outer face 2 of the lens is naturally convex with radius somewhat deviating from that of the inner face in magnitude, in order to provide the desired dioptric power. In the outer rim portion R, the curvatures or radii, respectively, deviate from the central values in the following manner: On the outer face, an annular part 4 with stronger (inward) curvature, thus smaller radius, is radially contiguous to the central portion. To this part, another may be outwards contiguous which is again less curved, conical (thus non-curved) or slightly outwardly (i.e. negatively) curved portion 5. In terms of magnitude, the curvature here is always less (i.e. the radius larger) than in the first mentioned transition region 4, i.e. the lens smoothly terminates.
The inner face 1 also has an annular region radially contiguous to the central region with the elliptical face, which, however, is less curved, thus more flattish, corresponding to a larger radius of curvature in this region. Herein, the radius of curvature in a sectional plane is meant, which plane contains the optical axis of the lens. The line formed by the inner face and the sectional plane forms a point of inflection 6, i.e. the curvature of the line first becomes zero and then positive. For the Gaussian surface curvature, this means a transition to negative values. To this region, the region 7 is contiguous, where the inner face of the contact lens approaches to the global tangential plane; here, the curvature in the main section perpendicular to the radial sectional plane is zero, so that the Gaussian surface curvature becomes zero and still further outside, in the immediate edge region, again transitions to positive values.
Between these two points (in the sectional plane) or lines (on the surface) of curvature inflection 6 and 7 there is a region in which the contact lens gradually lifts, when viewed radially from inner to outer region, from the cornea. This region is crucial for the wearing comfort. As recognized by the inventors, in this region there should neither be formed an overly sharp edge, which might interrupt the film of tear liquid present on the cornea or might even cut into the cornea; nor should the rim region have an outwardly pointed, protruding, strongly curved edge (“Skispitzen-Profil”), which might irritate the eyelid slipping onto it from outwards during blinking. Rather, the annular regions according to the invention, smoothly transitioning towards an outer edge free from any sharp edges, (see
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From the proceedings of the process an irregularity of the outer results insofar as it deviates from an exact circle line, other than known e.g. from punched lens contours. Because also the cornea never has exactly regular contours, this deviation from an ideal shape not only is not detrimental, but even has beneficial effects on the wearing comfort. The amount of the irregularity may be quantified by assigning, by calculation, an ideally approximating circle line to the projection of the outer rim, according to the criterion of a minimum sum of the squared deviations. The, the average square deviation is a measure of the irregularity, and is at least 5000 μm2 (converted to magnitudes: about 1% of half the lens diameter), but in embodiments may be more than 1000 μm2 or more than 10000 μm2.
The contact lenses formed according to the invention may be used as cover lenses, i.e. with or without refractive power for physically protecting the cornea from irritations. This may be useful as a flanking, itself non-therapeutic measure for a medicinal-therapeutic eye treatment.
In the subsequent claims, “mainly consisting” is understood as amass proportion of more than 50%, in particular of more than 90% up to entirely. “Curvature” is in each case the inverse radius of curvature, i.e. the radius of the approaching circle, wherein the sign is positive for convex surfaces and is negative for concave surfaces. The Gaussian surface curvature is the product of the two principal curvatures, thus is negative when both the principal curvatures have different signs (saddle surface), and is zero when one or both principal curvatures are zero (e.g. cylinder and conus surface).
The skilled person will realize that deviations from the embodiments described above are possible without leaving the scope of protection of the appended claims.
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21. A silicone contact lens, having a radial cross-section on an inner face of the contact lens that includes a rim region between a point of inflection and the outer edge, in which the contour of the cross-section is convex,
- said contact lens comprising a hydrophilizing surface coating having the water contact angle of less than 10°.
22. The contact lens of claim 21, wherein the minimum radius of the convex contour of the cross-section is in the range 0.1 mm-10 mm.
23. The contact lens of claim 22, wherein the hydrophilizing layer consists mainly of (meth)acrylic acid units.
24. The contact lens of claim 22, wherein the hydrophilizing layer is thicker than 1 gm.
25. The contact lens of claim 21, wherein the silicone is poly(dimethylsiloxane).
26. The contact lens of claim 21, wherein the rim region of the contact lens has a width in the range of 1 μm to 1 mm.
27. The contact lens of claim 21, wherein the outer edge of the contact lens has an irregularity, wherein a circle line ascribed to the outer edge according to the criterion of least mean squared deviations has an average squared deviation of at least 5000 μm2.
28. A method of manufacturing a silicone contact lens, wherein a female mold part and a male mold part are provided, and a silicone precursor material is introduced between the mold parts and is polymerized between the mold parts, said method comprising:
- releasing the polymerized contact lens form the mold using a liquid swelling the contact lens without generating a cutting edge; and
- hydrophilizing the polymerized contact lens in a combined PECVD/CVD-process.
29. The method of claim 28, wherein the contact lens is coated with cross-linked (meth)acrylic acid units.
30. The method of claim 28, wherein a first coating step occurs in a low-pressure plasma.
31. The method of claim 30, wherein a subsequent coating step occurs from the gas phase without the action of a plasma.
32. The method of claim 28, wherein a non-polar liquid is used for releasing the contact lens from the mold, a dipole moment of which is less than 0,2 Debye.
33. The method of claim 28, wherein the released contact lens is treated with a polar liquid, the dipole moment of which is more than 1 Debye.
34. The method of claim 28, wherein, while the reaction mixture is still liquid, the mold parts are rotated with respect to one another in order to separate the part of the reaction mixture intended for forming the contact lens from excess material.
35. The method of claim 28, wherein the contact lens comprises a hydrophilizing surface coating, the water contact angle of which is less than 10°.
36. A contact lens made according to the method of claim 28.
37. The contact lens of claim 21, wherein the minimum radius of the convex contour of the cross-section is more than 0.5 mm.
38. The contact lens of claim 21, wherein the rim region of the contact lens has a width in the range of 0.01 mm to 0.1 mm.
39. The contact lens of claim 21, wherein the contact lens comprises a bandage contact lens.
40. The method of claim 28, wherein the contact lens comprises a bandage contact lens.
Type: Application
Filed: Feb 1, 2013
Publication Date: Feb 5, 2015
Applicant: LENSWISTA AG (Berlin)
Inventors: Martin Görne (Hamburg), Thomas Kordick (Goldbach)
Application Number: 14/004,760
International Classification: G02C 7/04 (20060101); G02B 1/04 (20060101);